This idea has been reinforced by several lines of indirect evidence: first, myelin-reactive T cells were isolated from both the blood and cerebrospinal fluid of MS patients (12, 13); second, an exacerbated outcome was reported in MS patients treated with a myelin basic protein–derived altered peptide ligand (14); finally, some MS risk variants (e.g., HLA-DRB1*1501) were associated with antigen presenting process (15). This evidence concerns the gene HLA-DRB1 and myeloid sarcoma.